import com.fasterxml.jackson.databind.ObjectMapper;
import com.mysql.jdbc.jdbc2.optional.MysqlDataSource;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.sql.DataSource;
import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

class Message{
    public String from;
    public String to;
    public String mess;

    @Override
    public String toString() {
        return "Message{" +
                "from='" + from + '\'' +
                ", to='" + to + '\'' +
                ", mess='" + mess + '\'' +
                '}';
    }
}

@WebServlet("/message")
public class massageWallServlet extends HttpServlet {
    ObjectMapper objectMapper = new ObjectMapper();
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        List<Message> messageList = locd();
        String reString = objectMapper.writeValueAsString(messageList);
        resp.setContentType("application/json; charset=utf8");
        resp.getWriter().write(reString);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        Message mes = objectMapper.readValue(req.getInputStream(),Message.class);
        save(mes);
        System.out.println("消息提交成功 message = "+ mes);
    }

    private void save(Message message) {
        DataSource dataSource = new MysqlDataSource();
        ((MysqlDataSource)dataSource).setUrl("jdbc:mysql://127.0.0.1:3306/wall?characterEncoding=utf8&useSSL=false");
        ((MysqlDataSource)dataSource).setUser("root");
        ((MysqlDataSource)dataSource).setPassword("040825lj");

        try {
            Connection connection = dataSource.getConnection();
            String sql = "insert into wall values(?, ?, ?)";
            PreparedStatement statement = connection.prepareStatement(sql);
            statement.setString(1, message.from);
            statement.setString(2, message.to);
            statement.setString(3, message.mess);
            statement.executeUpdate();

            statement.close();
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    private List<Message> locd() {
        List<Message> list = new ArrayList<>();
        DataSource dataSource = new MysqlDataSource();
        ((MysqlDataSource)dataSource).setUrl("jdbc:mysql://127.0.0.1:3306/wall?characterEncoding=utf8&useSSL=false");
        ((MysqlDataSource)dataSource).setUser("root");
        ((MysqlDataSource)dataSource).setPassword("040825lj");
        try {
            Connection connection = dataSource.getConnection();
            String sql = "select * from wall";
            PreparedStatement statement = connection.prepareStatement(sql);
            ResultSet resultSet = statement.executeQuery();
            while(resultSet.next()) {
                Message message = new Message();
                message.from = resultSet.getString("from");
                message.to = resultSet.getString("to");
                message.mess = resultSet.getString("message");
                list.add(message);
            }
            resultSet.close();
            statement.close();
            connection.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return list;
    }
}
